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Heavy Duty Conveyor Drives at Hydroelectric Plant Construction

Belt Conveyor Drive Systems

Heavy Duty Conveyor Drives at Hydroelectric Plant Construction

Industrial Gear Units at “Linthal 2015” Construction Site in Switzerland

To stabilise the power grid, Swiss supplier Linth-Limmern AG extends its existing Limmern power plant by a pump storage system. Most of the necessary installation is situated underground, and during construction a huge amount of rock material had to be moved from almost 600 m inside the mountain.

By:

Jörg Niermann

(ed. WoMaMarcel - 27/7/2015)

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Drive Systems for Conveyors

The huge chambers for the pumping station were excavated from top to bottom. Work proceeded rapidly in an intensive 3-shift, 24/7 operation. Every day, about 800 m3 of rock were removed. The excavated material was reused in the construction project. Two S-conveyors each transported about 500 tons of material per hour over a distance of about 260 m with a steep incline of 45 degrees and a height difference of around 180 m. A first conveyor transported the excavated material down to a crushing plant. It was driven by a Nord industrial gear unit with brake control, which also generated electricity. A second conveyor transported the crushed material up to the gravel plant, where it was stored or directly used as construction aggregate for the dams and for concrete. Over a total of three years, these conveyors transported approximately one million tons of material. Placed to the right and left of this conveyor system and connected by a common shaft, two Nord industrial gear units with a 250 kW output moved the belts at 2.2 m/s.

Heavy-duty Gear Design

The industrial gear units for this huge construction project were based on Nord’s tried-and-tested one-piece housing design with no joints that are subject to radial forces or torque. The gear case is machined from a single cast-iron block. It integrates all bearing seats. This design provides for high precision, rigidity, and strength. The overlapping bearing offset allows for more compact gear cases and larger roller bearings that guarantee a long operating life. The industrial gear units in the “Linthal 2015” project featured IP55 ingress protection.

Nord manufactures industrial gear units for output torques up to more than 242 000 Nm with a one-piece housing, achieving relatively compact dimensions and maximum resilience.

Customer-oriented Solutions

The supplier of this complete drive solution was Getriebebau Nord AG, Switzerland, a member of the Nord Drivesystems Group. The drive specialists from Arnegg near St. Gallen place much value on close cooperation with customers. Guido Eigenmann, manager at Nord Switzerland, says: “We provide customer benefits – not just products. We offer a comprehensive service package and provide maintenance training, so that the customer knows what to look out for. It is particularly important for us to supply complete systems which are highly efficient and economically priced. Many users require not just drive components, but rather complete, ready-to-use system solutions. We tailor our drive solutions to each individual application.” Nord Drivesystems was commissioned by the plant constructor Marti Technik, a subsidiary of the Swiss Marti Holding AG and a provider of customized solutions focusing on underground construction work.

Ready for the next Challenge

After the completion of the conveying tasks, the Nord industrial gear units were disassembled by Marti Technik, and are now awaiting their next assignment. Ernst Kuster, head of maintenance and responsible for the conveyor systems at Marti Technik, says: “In compliance with the instruction manual, we changed the oil once, but that was the only maintenance measure we had to take over the course of three years. The Nord gear units performed brilliantly. Nord Drivesystems has cooperated with us very well. All of our requirements were catered for. The short delivery time is also remarkable – the built-to-order drives were delivered after about ten weeks. All in all we are very satisfied – a very good cost-benefit ratio, excellent support before and after sales.”